Conventionally, in LTE (Long Term Evolution), as the state of a mobile station apparatus, two states, that is, an “RRC CONNECTED state” and an “RRC IDLE state” are defined. The “RRC” here is an abbreviation for “Radio Resource Control”.
The features of the “RRC CONNECTED state” are as follows.                Radio connection is established between a mobile station and a base station, and packet communication can be performed.        A radio resource for performing the packet communication from the base station is allocated, and a notification is provided by a PDCCH.        Since in order to maintain radio connection in a time other than the time during which the power consumption is performed, the PDCCH is continuously received, power consumption is high.        
On the other hand, the features of the “RRC IDLE state” are as follows.                The radio connection is not established between the mobile station and the base station, and the packet communication cannot be performed.        When the packet communication is performed, the radio connection is established, and it is necessary to make transition to the “RRC CONNECTED state”.        Paging (incoming information) from the base station is intermittently received.        Power consumption is low.        
When the mobile station performs the packet communication, the radio connection to the base station is established, and the packet communication is performed in the “RRC CONNECTED state”. Even after the completion of the packet communication, in order to prepare for the subsequent packet communication, the radio connection is maintained for a given period of time in the “RRC CONNECTED state”. Then, when the state of non-communication is continued for the given period of time, in order to increase the efficiency of the radio resource and to lower the power consumption of the mobile station, the radio connection is interrupted, and the state is made transition to the “RRC IDLE state”.
When as described above, the mobile station is made state transition between the “RRC CONNECTED state” and the “RRC IDLE state”, a plurality of control signals is exchanged between the mobile station and the base station. When the mobile station frequently repeats the state transition, a large number of control signals are generated, and thus a large load is placed on a network. Hence, it is necessary to minimize the number of control signal for the mobile station.
Hence, a technology disclosed in patent literature 1 proposes that the function of detecting whether or not the packet communication transmitted and received by the mobile station is present is provided in the base station, and that when the packet communication is not performed for a given period of time after the completion of the packet communication, the mobile station is made transition to the “RRC IDLE state”.